Method of generating formers for contour-grinding machines



B. M. w. HANSON. METHOD OF GENERATING FORMERS FOR CONTOUR GRINDING MACHINES;

Patnted June 1, 1920.

APPLICATION FILED OCT- 29,1918.

' 5 SHEETS-SHEET I.

nvvavror; M 1 41M BY I 7' A ORNEY 8. M w. HANSON. METHOD- OF GENERAUNG FORM'ERIS FOR comqun GRINDING magmas.

Patented J me 1, 1929.

5 SHEETS-SHEET 2 B. M. W. HANSON.

METHOD OF GENERATING FQRMERS FOR fiGNTQUR GRINDING MACHINES.

APPLICATION FlLEB'flCT-ZQ, 1M8. 1,341,800.

Patented June 1, 1920.

INVBHOR m. W. Wm y! 14% A GENE? 8. M. w. HANSON.

METHOD OF GENERATING FORMERS FOR CONTOUR GRINDING MACHINES.

' APPLlC-ATION FYI-LED 00129, 1918.

v Patented June 1, 1920.

5 SHEEIS-SHEET 4.

IN I/EN TOR A ORIVE Y8 B. M. w. HANSON. METHOD OF GENEBATINQFDBMERS FOB CflNTOUR GRINDING MACHINES.

1,341,808 APPLlCATiQN FILED BET-29. 1918- 5 SHEETS-SHEET 5;

luff-1102' I). W: Mu .m

tion for'contour BENGT m. w. HANSON, on mnrronn,

connncrrcu'r, ASSIGNOR 'ro P ATT &

WHITNEY COMPANY, OF NEW YORK, N. Y.,-A'CORPORA.TION OF NEW' METHOD or ennnnnrme ronmnns non. CONTOUR-GRINDING- MACHINES.

To all wkomjt may concern:

Be it known that I, BENGT M. W. HAN- soN, a citizen of the United States, residing at Hartford, in the county of Hartfordan'd State of Connecticut, have invented certain new and useful Improvements in Methods of Generating Formersfor Contour-GrindingMachines, of which the following is a specification. I I

This invention is particularly adapted for; generating formers such as are used with contour grinding machines of the type set forth in my copendin application for metal reducing machines, I

June 8th, 1916, and my, copending applicaerial No. 102,458, filed rinding machines, Serial No. 247,631, filed uly 31st, 1918. Machines of this type require a special former dif-- fering' from the normal former when they are to be used for grinding cutters having shovel teeth; that is, teeth with cutting faces inclined. backward and inward with v claims without in accordance with this invention and adapt- .a simple method whereby such special formers can be easily and accurately generated.

.In the accompanying drawings I have illustrated a grinding machine which. is substantially the same as that shown in my aforesaid copending application Serial No. 247,631, in order that my improved method may be fully understood. The grinding machine of itself constitutes no .part of the present invention, and it will be understood that the drawings are intended to be merely illustrative and that various changes may be made within. the scope of the appended departing from the inven-' tion. a

Of the drawin Figure 1 is a pin view of a grinding machine .adapted to use a former generated ed to be used during the generation of the former.

Fig. 2 is an end view of the grinding m a-' chine.

Fig. 3 is a plan View of a formed cutter selected for purposes of illustration, it being understood, of c0t1rse,that the contour I Specification of Letters Patent. I Patented June 1, 1920; Application filed October 2 9, 1918. Serial No. 260,210.

may be varied infinitely in accordance with re ulrements.

UNITED sTAr s- PA E ig. 4 is an end view of the'cutter shown in Fig. 3, the viewalso showing a grinding o n I F g. '5 1s a plan new of a former such'as' wheel in operative relation to the cutter.

is used for guiding the grinding wheel to grind the teeth of a cutter such as is shown in Fig. .3. i

Fig. 6 an end view similar to Fig. 4 butshowmg a cutter havin' undercut or shovel teeth, the efl 'ective con our of the cutter being understood to be the same as that' of the cutter shownin Fig. 3.

Fig. '7 is an end view, on a greatly enlarged scale, of a fragment of the cutter' p v.

shown in Fig. 6. Fig. 8 is a fragmentary face view of one tooth of the cutter shown in Figs. 6 and 7 v Fig. 9v-is a dia rammatic view showing the mounting of t e former blank.

Figs. 10, 11 and 12 are diagrammatic views showing respectively the successive steps which are followed in the generation of a former in accordance with the invention.

. Fig. 13 is a diagrammatic view showin another step in the generation.

Fig. 14 is a front view of the preferred 7 form of apparatus adapted for practising the Invention, this apparatus being shown as mounted on a grinding machine such ,as.

shown in Figs. 1 and 2. I

Fig. 15 is .a plan view of the apparatus shown in Fig. 14.

Fig. 16 is an end view of the apparatus shown in Fi 14. I

In order t at my improved method may be clearly understood, I will first briefly degrinding machine as shown in scribe the Figs. 1' and 1 represents the'main frame of the machine which is or may be mounted upon a base or pedestal 2 of any desired-construction. The frame 1 is in the form of a hollow box orhousing within which is mounted a pantographic mechanism for supporting and controlling the movement of the grinding wheel. This permits the'wheel to move horizontally. in any direction, but holds it in paralellism while being so moved. Two par- "allel links 3 and 4 are. suitably pivoted at 5 and'.6 respectively in the main housing 2 and are pivotedto a cruciform member 7 which is thus mounted for movement forward and backward in parallelism. The cruciform member 7 is provided with two sets of vertical pivots which engage parallel links 8 and 9. -These links extend forward through openings in the frame and at their forward ends are pivotally connected with a plate 10.

By means of the pantographic connections which have been described the plate 10 is freely movable horizontally inany direction, but is nevertheless always maintained in parallelism. The grinding wheel is carried by the plate 10 by means of'devices to be described and is thus bodily movable with I respect to the cutter or otherpart to be ground.

Hinged to the main frame 1 at 11 is a bed plate 12. This plate 12 together with the devices carried thereby can .be swung upward about the hinge axis to expose the link--' age and other parts contained within the housing 1. -To the plate 12 are secured; the

.devices which support the cutter or other part to be ground. For holding the" cutter to be ground, or for holding the special fixture embodying the present invention, I provide a hollow work spindle 13 which is rotatable in a bearin 14. If the cutter has a shank this may be inserted directly into the spindle, or if the'cutter has no shank it may be mounted on an arbor which may be in;

serted into the spindle. As illustrated, there e screw-'controlledfby-a.

. In grindinga is a cutter A mounted on an arbor B. The spindle can be turned b imeans of aknurled knob 15 and the spinle can be locked in any desired position b means of a clamping and lever 16.

d cutter it is usually necessa to inde sented'in proper'lfrelation to the gun mg wheel. Toassiflst'iji'n indexing, I preferably provide a mechanism adapted -to directly engage t e front surfaces of the teeth. As illustrated, this-mechanism comprises a stop finger 17 carried by a series of rods. 18,

19 and 20 which are adj ustably connected and which can be secured in any desired relative positions by means of clamping screws.

The rod 20 is carried by the bearing 14 and can be clamped by means of the clamping screw 21. It will be seen that by means of these several rods. the stop 17 is universally adjustable.

Preferably the bearing 14 is carried by a slide 22 which is movable forward and backward under thecontrol of a screw operated by a hand wheel 23. The slide 22 is mounted on a second slide 24 which is movable transversely on ways carried by the plate 12.- For.

moving the slide 24 there is provided a screw 1 jcutter in order that .the',teet thereof may;..-be successively operatedby a. handwheel er Preferably I provide an outboard or tailstock bearin 26 arbor B when such an arbor is used. This bearing is adjustable into alinement with the bearing 14.;

Carried by the plate 10 is a grinding wheel supporting bracket 27 which is vertically pivoted to the plate by means of a pivot :pin28. The upper part of the bracket is provided with vertical ways along which is which can be used to support the end'o the; 10.

movable a slide 29. This slide is controlled the bracket 27 may be locked in any desired I position of angular adjustment, there is provided a rod 38 pivoted to' the plate 10. means of a bolt 39 the bracket. can be frictionally connected to the rod so as to lock the bracket 27 and the associated parts in any desired position.

At the front of the machine are notches adapted to receive projections 40, 40 on a former plate 41 whichis used to guide the plate 10 and associated parts as they are moved transversely. The former may be constructed in two sections, as shown in myaforesaid copending application, Serial No. 247,631, but for the sake of simplicity I have herein shown it as constructed in one piece.

For securing the former there is provided. a- I clamping plate 42 and .a clamping screw 43 whic extends through .anotch 66 in the former. The bracket 27 carries a former stud 44 which is adapted to' engage andco operate with the former 41.

In operation a wheel 37 is selected having a width such that it can enter all of the depressions in the cutter and follow all of the grooves of the contour, and a former stud 44 is selected having the same width as the wheel. For a left-hand cutter such as is shown, the grinding wheel is adjusted vertically so that its axis lies'a suitable distance a below the axis. of the cutter, this being-effectedby means of the screw 30 and-the nut 31.- This adjustment permits the wheel to cut deeper behind the cutting face of each tooth than at the cutting face, thus providing the necessary relief. For a right-hand cutter the wheel isadjusted so that its axis occupies a corresponding. position about the axis of the cutter. Initially, the grinding wheelis positioned with its plane of rotation at right angles to the cutter axis and is held in this position by means of the rod 38. The cutter to be ground is put in place which corresponds in contour to the contour of the cutter to be ground, and this former is clamped in place by means of the plate 42 and the screw 4.3. By means of the hand wheel 25 and the slide 24 the cutter is adjusted axially so as to bringit into proper relationship with the. former. To bring the cutter and the wheel into operative engagement with each other after the preliminary adjustments have been made, the slide 22 is moved by means of the hand wheel 23,

The operator then moves the wheel longitudinally of the cutter at the same time pressing inward to cause the former stud 44 to follow the contour of the former 41. If necessary, the wheel is moved along the cutter several times until grinding of the tooth is completed. Then thecutter is indexed, use being made of the stop 17 to insure the rotation of the successive teeth to the same position. v v

Figs. 3 and 5 show' the cutter and the formeron a somewhat larger scale.- The cutter is indicated as having a maximum radius R and a minimum radius B. Fig. 4 shows, on the same scale, the relationship between the grinding wheel and the cutter. It will be observed that the axis of the wheel is set below the axis of the cutter by a distance a as already pointed out in the description of the grinding machine. The wheel therefore acts upon the cutter 'at a plane which is parallel to the axis of the wheel but separated therefrom by the distance a. As fully set forth in my copending applications, the wheel is so dressed that its edge has a cross sectional contour which is semicircular in the said plane.

Fig. 6 shows the relationship between the grinding wheel and a cutter A having undercut or shovel teeth. This cutter also has a maximum radius R and a minimum radius R, the contour bein the same as that of the cutter shown in ig. 3. -From this view it will be noted that the axis of the grinding wheelmust be set below the axis of the cutter not only through the distance a to provide for the relief but also The former 'to be used for grinding the cutter A must have a contour which corresponds tothe contour of each tooth at the front surface thereof. It will be obvious that thiscontour will differ slightly from.

.to conform approximatel contour,- and in fact may initially have the plane passing through the effective contour of-the cutter wheniit is I Y observed that theoutermost point m of the tooth contour must beswung merely through an angle 0 to reach the plane of maximum depth of cutting, whereas the innermost point 0 of the tooth contour must be swung through a greater angle 8 to reach the Said plane of maximum depth of cutting. Of course, a point such as n on the contour at an intermediate distance from the axis must be moved through an intermediate angle such as d. Ordinarily in practice the angle 0 is 6, though so far as my invention is concerned, thls angle may be varied as (lowhich it will effect the deepest cutting; and

the innermost point '0 lies at a still greater distance t to the right of the position at i which it will effect the deepest cutting. From a consideration of Fig. 7 it will be clear that the front contour of each tooth varies from the true effective contour, the amount of variation at any given point depending on the radius at that point.

In generating a former to beused in grinding a cutter A, use ismade'of a machine such as shown in Figs. 1 and 2 and a former such as 41 is mounted. in the usual position in'the machine. By means of a the machine in approximately thev position. which the .cutter ordinarily occupies,- as

shown in Fig. 9. The normal position of the cutter axis is indicated at f. This former blank 41 is preferably preliminarily shaped to the desired same contour-as the former 41.

' Preferably-the grinding wheel isset with wheel in this case having a semi-circular 1 cross sectlonal edge contour in a plane passing through the axis, which plane in the present instance constitutes the grinding plane of the wheel.

The blank 41 is mounted with its top surface at a distance from the center f which is the same as the distance between the plane of the front surface of a tooth and the axis of the cutter, this distance being I),

as shown in Fig. 6;- As shown in Fig. 9, the blank is preferably so adjusted that a perpendicular line erected at its front edge or outermost point m lies at a distance R from the axis f. Obviously a perpendicular line erected at the innermost point 0. of the con tour of the blank will lie at a distance R :from the axis f.

A The former -blank having been thus mountedwith respect to the axis f, is then swung u ward throu h "the angle 0, as shown in ig. 10. The ormer is then bodily moved with-respect to the wheel to a pos1- tion such that the axis 7 is at a distance R from-the grinding surface, when the former pin 44 is in engagement with the outermost part of the former 41. This upward swinging of the .former blank moves the front edge thereof toward the right a distance equal to r, as shown in Fi 7 The wheel is then passed along the sur ace of the former points along the topsurface of the b which are at smaller distances from the -of the axis 7,

center, but this also is immaterial.

After grinding is. complete, as illustrated in Fig. 10, the blank is inclined to a greater angle such as d-as shown in Fig. 11, and the grinding is repeated without adjusting the wheel or changin in any we. the position ft willbe 0 car that this increased inclination 'of the blank carries the outermost points thereof above the grinding plane, and these therefore are carried out of the range ofactionof the grinding wheel.

The increased angle, however, permits the wheel to act on intermediate points of the. 'blank such as n" and to grind them back a distance a from the initial positions.

Then the blankis still further inclined to"- the angle ,6, as shown in Fig. 12. This increased inclination carries the. parts alreadyground outv of the range of action of the 7 wheel and permits the wheel to have access to the innermost points o'" of the blank and grind themback a-distanee t.- -Whj1e I'have' 45- illustrated butfthree positions' of inclination .of the former-.blankyduring generation, it

will-be understood thatin practice; it is preferable to, with' the-first position, as

shown .in vFi'g;?il(l,}ttmifthen, .by, a suitable mlmber of: very minute changes, move the blank to thefinal'positioneshown in Fig. 12,

' passing the wheel ver the blank after each change of -o sitio1'1. j The res t. of the several grindingo top surface of. the former blank is provided with a contour-which is exactly the same as the contour of the .front plane of a.-tooth of the cutter A. It is to be noted, however,-

that owing tof-the relationship-between the blank and the'wheel', as shown-in Figs. 10 to 12, the lower arts of the blank are backward sot t they-donot have contour. The thin uppe v v peratlons lllustratedi'n Figs. 10 to-12 is that the lgl'round e true I r edge-0f the former resultmg'fromthe shown in and this former could be put in normal posi- -10 "to s is absolutely acetate atom;

tion'on themachine for grinding a-cutter. i

such as A. It is not well adapted for this purpose, however, as the thin upper edge,"

thereof would become worn after use,- thus causing inaccuracies. I therefore prefer to. U

use thls former thus generated merely as a ma'ster former and to generate fromit an operating former having a perpendicular front edge. v This is done simply by putting the master former 41 in normal pos1t1on 1n the machine and securing a blank 41'. in the machine in'horizontal position, as shown in Fig.13. The wheel is passed over this blank 41 using the master-former 41' as a guide,

and, if necessary, either the wheel or the I blank is vertically adjusted from time to time so as to. provide a perfectly straight and perpendicular edge at the front of the blank.- After the blank 41" has been thus completely ground, it is ready for use in the ter such as A.

- In Figs. -14, 15 and 16' I have illustrated apparatus which may be used for. carrying out the process steps illustrated in Figs. 9 to is provided with trunnions 46 and 47 adapted respectively to be seated in the bearings 14 and 26. Rotatable on the trunnion 46 1s a collar 48 having an arm 49 which is pro-. 'vided with a notch adapted to receive-the rod 20 and thus hold the. collar against rotative movement. Adjacent the collar 48 is: a flange 50 which is ri d. with the frame with graduation.

and which is provid marks. to represent angles. Ooiiperating with these graduations is a mark 51 on the collar.48, and bythese means the frame 45 may be adjusted through an desired angle.

machine in the usual way for grinding a cut '13. This comprises an arch frame 45 which After adjustment it may be ocked by means of the screw 16.

The frame 45 is provided with vertical wa s along which is movable a slide 52.

of a screw 53 and a nut54, and it can be locked in adjusted position by means of a .nut 55. At 56 the slide'is provided with gra'duations adapted to coiiperate' with a -mark' 57" on the frame- By this means the extent of vertical adjustment of the 'slide can be =determined.- I

The slide 52 is provided with horizontal" ways along which is movable asecond slide 58. This second slide 58fcan be controlled slide 58 is provided with a mark 61 adapted to cognate with graduations 62 on the slide 52 y these means the extent of horizontal .adjustment of the slide can be determined.

At the bottom of the slide 58 there is provided a clamping plate 63 and a clamping screw 64 which canbe used to hold a former blank such as 41'.

, by means; of a screw 59 and a nut 60. The I 1 10 Thisslide is vertically adjustable by means The apparatus which has been described is so constructed and proportioned that the former blank 41 is held in operative rela; tion with the grinding wheel 37, as illustrated. The adjustment of the blank to bring the top surface thereof a'distance 6 below the axis, as shown in Fig. 9, is efiected by moving the slide 52 downward through the proper distance, as measured by the scale 56. The former blank is horizontally adjusted to bring the outermost point adistance R from the axis by moving the slide 58, the distance being measured on the scale 62. After these adjustments have been made the former can be inclined to the proper angle by turning the whole frame, the amount of the angle being measured by the graduations on the flange 50.

From the description which has already been given in connection with the diagrammatic views, it will be understood that the former blank, after having been adjusted as described, is firstinclined through theangle c and the Wheel is then passed over it. Then the angle of inclination is slightly increased and the wheel again passed over the blank. This operation is repeated until the inclination finally reachesthe angle After this final grinding the master former is complete and is ready to be substituted for theformer 41 to be'used for generating the operating former, as illustrated in Fig. 13. It will be understood that in generating this operating former the fixture is so adjusted'that the former is held horizontal. Relative adjustment during grinding of the operating former to insure a straight perpendicular front edge can be made either by moving the slide 52 upward or downward or by moving the Wheel upward or downward.

What I claim is:

1. The herein described method of generating a former for use in grinding a' formed milling cutter having teeth with the planes of their front faces separated from the axis, the method consisting in mounting a blank for movement about a pivotal axls in the grinding plane of a grinding wheel, in off-setting the blank from the pivotal axis, in inclining the blank and grinding it by the wheel under the guidance of a former pin and of a former having'the same contour as the effective contour of the cutter, and in successively increasing the angle of inclination and repeating the'grinding as aforesaid.

2. The herein described method of generating a former for use in grinding a formed milling cutter having teeth with the planes of their front faces separated from the axis by the distance I), the method consisting in mounting a blank for movement about an axis f in the grinding plane of a former pin and of a former having the same contour as the effective contour of the cutter, and in successively increasing the angle of inclination without changing the relation between the axis f and the former pin and former and repeating the grinding as aforesaid until the angle e is attained.

3. The herein described method of generating a former for use in grinding a formed milling cutter with the maximum radius R and the minimum radius R and having teeth with the planes of their front faces separated from the axis by. the distance Z), the method consisting in mounting a blank for movement about an axis f in the grinding plane of a grinding Wheel, in off-setting the blank from the axis through the distance Z), in inclining the blank at the angle 0 corresponding to the maximum radius R, in then grinding the blank by the wheel under the guidance of a former pin and of a former having the same contour as the effective contour of the cutter, and in successively increasing the angle of inclination Without changing the relation between the axis fand the former at the angle 6 corresponding to the minimum radius R.

.4.'The herein described method of generating a former for use in grinding a formed milling cutter having teeth with the planes of their front faces separated from the axis by the distance 6, the method consisting' in mounting a blank for movement about an axis 7 in the grinding plane of a grinding wheel, in off-setting the blank from the axis through the distance I), in inclining the blank at the angle 0, in then grinding the blank by the wheelvundcr the guidance of a former pin and of. a former having'the same contour as the effective contour of the cutter, in successively increasing the angle of inclination without changing the relation between the axis 7" and the former pin and former and repeating the grinding as aforesaid until the angle e is attained, and in using the former thus generated as a master to generate an operating former having its contour surface perpendioular to its parallel outer surfaces.

In testimony signature.

whereof, I hereto 'aliix my BENGT M. W. HANSON.- 

